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Old 02-21-2001, 03:50 PM   #1
Shik
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Post "Up-Pipe" cat replacement info?

Sorry if this was covered before( did a search but didn't find anything specific).

I just recieved the new Hyper Rev " New Impreza STi Perfect Guide", and noticed a shot of a factory up pipe with the cat in it that had a O2 sensor right between the cat and the turbo( ), obviously making it difficult to simply throw in a "test pipe" for those who desired to do so.

I was curious if any of you that crawled under the Impreza here in the US noticed the same O2 sensor( can't see why we wouldn't get one).
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Old 02-21-2001, 07:27 PM   #2
DeliciouSpeed
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The same O2 sensor will be there, Rallispec has plans for a replacement pipe.

Ken
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Old 02-21-2001, 08:57 PM   #3
XT6Wagon
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Uh, its not hard at all to move said O2 sensor to behind the turbo, while you are removing the cat. They do after all put in O2 sensors in custom exaust pipe every day at exaust shops across the nation.
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Old 02-22-2001, 01:06 AM   #4
Shik
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Uh, you missed my point entirely. It doesn't matter where you put the O2 sensor. Being that the first 02 sensor is right after the first cat( which many have expressed a desire to replace with a test pipe such as RalliSpec's which to my knowledge does not include a cat),if the cat is removed, the readings from the O2 sensor are obviously going to be different, thus possibly causing a "check engine" light.

In the various disscussions involving fitting a "test pipe" in place of the OEM cat-fitted up pipe, I did not see any mention about the O2 sensor that is monitoring the performance of the first cat that everyone wants to delete.

I wasn't asking because I didn't know where the O2 sensor would be mounted after the OEM pipe was gone. Jeeze man, I did have a few exhaust systems made in the past.
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Old 02-22-2001, 09:14 AM   #5
Brahmzy
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I sure hope there is a work-around for those cats. I don't want my CE comin' on.
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Old 02-22-2001, 10:25 AM   #6
j00z
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check out the O2 sensors on the pics I took:
http://www.i-club.com/ubb-files/Foru...ML/000686.html
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Old 02-22-2001, 02:38 PM   #7
Tuning Factory Inc.
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I will be producing crossover and downpipes with provisions for the O2 sensor. I have a solution to the problem. Now I just need my car to take the mold. I do this for the Honda folks who run test pipes. It's not a hard thing to solve when you think about it.
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Old 02-22-2001, 02:51 PM   #8
DeliciouSpeed
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Mr G, won't call you god. But hey, have you manged to pull a cat on a stock ECU 96 up honda without the ECU going nuts? Or maybe I read you wrong.

Ken
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Old 02-23-2001, 12:48 AM   #9
GDA
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I did a Header swap on a 1996 Civic Dx, which has the cat built on to the header at the mid way of the block (4 primaries dump into cat at the top of engine). I swapped that out with a 92-95 style DC 4-2-1 header and put aftermarket 92-95 style cat on the bottom of car (normal area for most cars), and had new o2 fitting welded, no problems, no CE lights either, but my conversion is a bit different.

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Old 02-23-2001, 04:00 AM   #10
Shik
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That is a bit different since the WRX has three cats and most people wanted to get rid of the first cat in the up pipe and the second one in the downpipe and then put a hi-flow cat in the mid pipe. Surely if you move the O2 sensor from the up-pipe all the way back to after the cat in the mid-pipe, the readings would be a bit off and would probably still cause a check engine light.

Of course, there is always the chance that deleting the cat in the up-pipe will do nothing for performance, in which case this topic wouldn't matter at all.
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Old 02-23-2001, 07:13 AM   #11
DeliciouSpeed
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EJ, the DX is different, does not have two O2s. And the 96 was the easiest to get away with for all Hondas anyway.

Ken
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Old 02-23-2001, 07:41 AM   #12
Simon Lines
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Guys
Removing the cat (or reducing its effectiveness) WILL cause a check engine light (on the EU model)
Cheers
Simon
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Old 02-23-2001, 10:35 AM   #13
j00z
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AFAIK, all OBDII cars have 2 O2 sensors. One before the cat, one either in or after the cat. This was a change in the OBD system that had aftermarket tuners up in arms.

Replacing the one before the cat is nothing. It's when they are after or in the cats that's the tricky part.
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Old 02-23-2001, 11:35 AM   #14
zetecdan
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we will also be working on a replacement pipe as soon as the car comes in. From my experience with o2 sensors and workarounds, it shouldn't be that big of an issue. worst case scenario, we'll have a superchip made for the car (if possible) that will take the pipe into account, so the CE light doesn't come on.
dan
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Old 02-23-2001, 11:43 AM   #15
WRXRob
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How many O2 sensors does this exhaust have? It seems to me that if it only has two, you should be able to slap on in front of and one behind any cat in the system and everything would be alright. I find it hard to believe Subaru would have put in 4 or 5 O2 sensors to monitor all 3 cats.
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Old 02-23-2001, 06:35 PM   #16
BoostFreak
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On my 99 Regal GS, as with all OBD-II vehicals, there are also 2 O2 sensors. One in the downpipe, and one after the cat. It's there to check the efficiency of the cat. When I eliminated my cat, I installed a O2 spoof made by www.Casperselectronics.com . It worked flawlessly for my GS, but I don't know if it'll also work for the Subaru....
I'm about to sell my GS, and just put the cat back on. I was supposed to sell the spoof to a buddy, but I'll hold onto it and test it on the WRX.
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Old 02-23-2001, 11:41 PM   #17
Steve Theodore
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Cool

Is this "spoof" you're referring to the same thing as an O2 simulator? I've heard of those being used on OBD-II cars to fool the ECU when cats are removed.

Steve
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Old 02-24-2001, 01:30 AM   #18
BoostFreak
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Steve Theodore wrote
Is this "spoof" you're referring to the same thing as an O2 simulator? I've heard of those being used on OBD-II cars to fool the ECU when cats are removed.
Yep, O2 sim is another name for it. Luckily I only had one cat on my GS. I can't believe the Sub has 3! Lots of room for improvement.
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Old 02-25-2001, 01:29 AM   #19
Tuning Factory Inc.
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Yes I can make any OBD-II test pipe and downpipe but only make them for Hondas now. I use a piece of a small cat to fool the O2 sensor into thinking the cat is still on. Pretty simple solution and cheap of course. No need to fool around with the ECU. I myself will be going with a Power FC ECU so I will not have the problems associated with OBD-II. Remember, all JDM ECU's are OBD-I. OBD-II is only a North American regulation. Most UK ECU's whould be same as JDM spec.
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Old 02-25-2001, 01:38 AM   #20
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FOr reference, the MKIV board had instructions on how to make one yourself. This was the old link. It's not working at the moment. http://www.mkiv.com/techarticles/oxy...tor/index.html
Probably server problem.
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Old 02-24-2001, 04:08 PM   #21
DeliciouSpeed
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G-man you are the Shizz you know. I to, love the apex power FC, I hope they don't take to long to make it available, I may just get the link, it will be available very soon.
Keep us posted on the availability of your toys,

TIA,
Ken
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Old 02-24-2001, 04:27 PM   #22
Shik
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G, as far as the JDM Imprezas go, the picture in the New Hyper Rev with the up-pipe cat and O2 sensor was of a JDM car, and I recall SCC stating that all WRXs world wide will have three cats. So as far as sensors monitoring the cats, it seems everyone will have a bit of working out to do.

I also recall Brett Middelton from MRT stating that the new Imprezas are a bugger for fitting aftermarket exhausts due to O2 sensors and their placement on the new cars.

At least we will have the whole world working on a solution( if there is indeed a problem, as I mentioned before)
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Old 02-24-2001, 10:20 PM   #23
GDA
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Deliciouspeed the 96 civic dx did have 2 O2 sensores (obd2), and it isnt/wasnt the easiest of hondas to do that with.

non odbs are the easiest

yes WRX's are different i realize that.
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